Did you ever study yourself into exhaustion for an important test only to fail it when you finally took it? Worse, when you got the test back, you discovered that you must have spectacularly misremembered key facts.

Or has there ever been an occasion when someone tries to get you to remember something while you are very tired? You reach into a fatigue-fogged mind to remember what happened in an event and pull out a set of facts. The next day you are certain—positively certain—that things happened the way you remember them. But your version contradicts what everyone else remembers—and even recordings of the event.

In both cases you have fallen victim to fatigue-induced false memories. A recent study by German and Swiss researchers1 reveals that trying to recall facts when you are tired may lead to false memories. If a tired brain cannot find the “right” facts, it sometimes substitutes other ones. Then it hangs on to them. The false fact is accepted as the truth. And you retain confidence in that false answer the next day—leading to that disastrous result when you are tested on that material.

Hurts in Real Life

This does not affect just academics. It can hurt in real life. It is late, and you are tired. Did you pay the electric bill? You wrote a check, but you forgot to record it. Was it for the electric bill or something else? You think about it— long and hard.

Yes, you conclude—and end up getting a cutoff warning from the power company because you actually did not pay the bill. No, you decide—and send off another check, only to learn, after a month’s scrimping, that you have a credit on your next bill because you paid twice.

The best solution to the false memory problem is rest. You are better going to bed early, waking up early and reviewing the material while you are fresh. If you must make decisions when you are fatigued, do not rely on your memory, alone. Find sources on which to base your decision. Check a book, a video recording, or your written notes. (If you are diligent about recording your checks, your checkbook register would have told you whether or not you paid the electric bill.) Rely on those rather than your memory.

If you have to rely on memory alone, be willing to accept contradictory facts later on. Do not insist that your memories have to be right. Accept that you are more likely to have misremembered something because you were tired.